Capacity controlled refrigeration system



Filed June 28, 1966 Jan. 2, 1968 I .c. M. LEWIS 3,360,952-

CAPACITY CONTROLLED REFRIGERATION SYSTEM 3 Sheets-Sheet l FIGQI V IJ'VVEJVFOR. CARL M. LEWIS ATTORNEYS Jan. 2, 1968 C.'M.LEWIS 3,360,952

CAPACITY CONTROLLED REFRIGERATION SYSTEM Filed Juhe 2a, 1966 5 Sheets-Sheet 2 1N VENTOR. CARL M. LEWIS AT TO RNE YS C- 'M. LEWIS CAPACITY CONTROLLED REFRIGERATION SYSTEM Filed June 28, 1966 Jan. 2, 1968 3 Sheets-Sheet INVENTOR. CARL M LEWIS ATTORNEYS United States Patent 3,360,952 CAPACITY CONTROLLED REFRIGERATION SYSTEM Carl M. Lewis, Onalaska, Wis., assignor to The Trane Company, La Crosse, Wis., a corporation of Wisconsin Filed June 28, 1966, Ser. No. 561,125 Claims. (Cl. 62-196) This invention relates to bypass capacity control for compression type refrigeration systems.

In refrigeration systems of the compression type it is often desirable to increase or decrease the capacity of the system such as to correspond to the refrigeration load as bypassing compressed refrigerant from a portion of the discharge of the compression means back to the suction side of the compression means. This may be accomplished by placement of a valve in a bypass line which extends from the discharge side of a part of the compression means to the suction side of the compression means. By opening the valve, compressed refrigerant gas from part of the compression means flows directly to the suction without passing through the condenser, expansion means and evaporator thereby reducing the refrigerating effect of the system. Many such bypass unloader systems have been developed. The instantinvention affords certain advantages and is characterized by certain differences particularly in the manner in which the valve in the bypass line is actuated by gas pressures within the refrigeration system.

It is common practice to move the bypass valve to one of its extreme open or closed positions with a spring element and to move the valve to the other position by high side refrigerant pressure acting against the bias of the spring. Unfortunately the spring rate is relatively constant while the refrigerant pressure may vary, considerably particularly where an air cooled condenser is employed in cold weather conditions. Since one of the valve positions results from a balance between spring pressure and refrigerant pressure and since the refrigerant pressure varies while the spring rate is relatively constant, the bypass valve may flutter and cause excessive wear of the working parts as well as adversely affect the capacity control. It is even possible in such a system working under very cold weather conditions that insufiicient refrigerant pressure will be developed to actuate the valve against the bias of the spring at a time when capacity control is particularly desirable.

It is therefore an object of this invention to provide a refrigerant system which eliminates the above indicated failings and disadvantages of the prior art systems.

It is a further object to provide a refrigeration system with a bypass capacity control valve which does not flutter and which will not be adversely affected by variations in refrigerant gas pressure.

Another object of this invention is to provide a refrigerant system bypass capacity control valve Which does not require a spring as a prime motivating means.

A further object of the invention is to provide a bypass capacity control valve in a refrigeration system wherein the differential in pressure on the bypass valve opens the valve and the differential in pressure upon a piston closes the valve.

Another object of this invention is to provide a bypass valve actuator piston wherein one .side of the piston is continuously under high side pressure while the pressure on the other side is controlled between high side pressure and suction pressure.

Still another object of this invention is to provide a refrigeration system bypass unloader valve wherein the.

bypass valve is arranged on the downstream side of its seat and opening of the valve results from the differential in pressure across the valve.

Other objects and advantages will become apparent as this specification proceeds to describe the invention with reference to the accompanying drawing wherein like elements have been identified by like reference numerals in which:

FIGURE 1 is a diagrammatic View of a refrigeration system in corporating the invention including a portion of the compression means therefor;

FIGURE 2 illustrates a first for-m of unloader mechanism of the invention utilizing a three-way solenoid valve actuator;

FIGURE 3 illustrates a second form of unloader mechanism of the invention utilizing a three-Way solenoid valve actuator;

FIGURE 4 illustrates a third form of unloader mechanism of the invention utilizing a two-way solenoid valve actuator; and

FIGURE 5 illustrates a fourth form of unloader mechanism of the invention utilizing a two-way solenoid valve actuator.

Referring now to FIGURE 1, there is shown a refrigeration system 10 having a refrigerant condenser 12, a refrigerant expansion means 14, a refrigerant evaporator 16 and a refrigerant compression means 18 respectively serially connected in a closed refrigerant. circuit.

Compression means 18 has a first compression cylinder 20 and'a second compression cylinder 22 having pistons 24 and 26 respectively mounted therein and arranged to be reciprocated by crankshaft 28 through connecting rods 30. Compressor 18 has a valve plate 32 mounted at the end of compression cylinders 20 and 22 for admitting and discharging refrigerant to and from cylinders 20 and 22. Suction ports 34 and discharge ports 36 are disposed in plate 32 and communicate with first cylinder 26. Sue: tion ports 38 and discharge ports 40 are disposed in plate 32 and communicate with second cylinder 22. Suction ports 34 and 38 are each provided with an annular spring suction valve 42 and discharge ports 36 and 40 are each provided with an annular spring discharge valve 44. Valves 44 are provided with a stop member 45 to limit their open position.

Now with reference to FIGURES l and 2 it will be seen that disposed on the side of valve plate 32 opposite cylinders 20 and 22 is a cylinder head 46 which may be bolted to the cylinders as by bolts 48, Cylinder head 46 includes a suction chamber 50 which forms part of a suction passageway 51 extending from the outlet of evaporator 16 .to the suction, ports 34 and 38. Cylinder head 46 has a first cylinder discharge chamber 52 and a second cylinder discharge chamber 54 communicating respectively with discharge ports 36 and 40 for receiving refrigerant compressed in cylinders 20 and 22. Chamber 52 forms part of a first discharge passageway 56 extending from discharge port 36 to the inlet of condenser 12. Chamber 54 forms part of a second discharge passageway. 58'extending from discharge port 40 to discharge passageway 56. PassagewaySS has disposed therein a check valve 69 arranged to permit flow in passage 58 only in a direction away from chamber 54 toward passage 56.

. Chamber 54 also communicates with bypass passageway 62 defined by cylinder head 46 which extends to suction passageway 51 for bypassing refrigerant gas from discharge chamber 54 to suction chamber 50. A bypass unloader valve means 64 is provided for passageway 62 for controlling the flow of refrigerant gas therethrough.

Unloader valve means 64 includes an annular valve seat 66 through which passageway 62 extends and a valve 68 arranged on the downstream side of seat 66 in cooperative relationship therewith. Seat 66 may have external threads for sealingly securing it in passageway 62. Valve 68 is mounted on valve stem 70 for guiding of valve 68 to and from the face of seat 66. At one end of valve stem 70 is a valve stem guide 72 which may be secured to cylinder head 46 by ap ropriate threads.

Adjacent the other end of valve stem 70 is a cylindrical chamber 74 defined by cylinder head 46. Chamber 7-4 has a movable partition 76 therein dividing chamber 74 into a first portion 78 and a second portion 80. Partition 76 preferably is a piston slidably mounted for reciprocal movement along the axis of cylindrical chamber 74. Valve stem 70 slidably extends through a bore 82 in a wall defining the second portion 80 of chamber 74. Valve stem 70 is co-axially arranged with piston 76 and fastened thereto as by a nut 84. Thus it will be seen that movement of piston 76 toward portion 7 8 of chamber 74 affects closure of valve 68 and movement of valve 68 away from seat 66 affects movement of piston 76 toward second portion 80 of chamber 74.

The movement of valve 68 and piston 76 is controlled by the fluid pressures on these parts. Thus there is provided a passageway 86 communicating with first discharge passageway 56 with the second portion 80 of chamber 74. Passageway 86 communicates with passage 56 on the downstream side of check valve 58 thereby at all times placing second portion 80 of chamber 74 in fluid communication with the discharge chamber 52 of first cylinder 20.

The pressure in first portion 78 of chamber 74 is controlled between a high pressure equal to about the pressure in second portion 80 and a low pressure equal to about the pressure in suction chamber 50. In the form of the invention shown in FIGURE 2, this is accomplished with a three-way solenoid selector valve 88 having a first port communicating with passageway 56 via passageway 90, a second port communicating with suction passageway 51 via passageway 92, and a common port communicating with the first portion 78 of chamber 74 via passageway 94. Solenoid valve 88 also has a port operator 96 and a solenoid coil 98 for actuating operator 96.

When solenoid coil 98 is energized to move operator 96 to the right, first portion 78 of chamber 74 is communicated with and placed at the pressure of suction passageway -51 via passageways 92 and 94 whereby the differential pressure on piston 76 forces valve 68 to the closed position via stem 70 thereby loading the compressor, i.e. cylinder 22. It will be understood that second portion 80 is in continuous communication with passageway 56 via passageway 86 and the effective area of piston 76 is sufficiently greater than the face area of valve seat 66 so that valve 68 will close in spite of the differential pressure acting on valve 68.

When coil 98 is dc-energized and operator 96 is moved to theleft position by action of the bias spring 99, portion 78 of chamber 74 is communicated with and placed at the. pressure of passageway 56 via passageways 90 and '94 equalizing the pressure on both sides of piston 76 whereupon the differential pressure, on valve 68 forces valve 68 to the open position thereby unloading the compressor.

Solenoid coil 98 may be selectively energized by an electric circuit shown in FIGURE 1 including in series with coil 98 an electric power source 100 and a pressure switch 102. Switch 102 is constructed to open when the pressure at the evaporator 16 falls below-a predetermined value which is indicative of a low load on the refrigeration system. Thus as the load on the refrigeration system decreases to a predetermined value, switch 102 opens deenergizing coil 98 and unloading the compressor. When the load on the refrigeration system increases above a predetermined value, switch 102 closes, energizing coil 98 and loading the compressor.

The form of the invention shown in FIGURE 3 is similar to that shown in FIGURE 2 and elements having similar functions have been identified by similar reference numerals followed by the suffix a. The form of the invention shown in FIGURE 3 differs from that of FIGURE 2 mainly in that the position of the valve stem guide 72 and the cylindrical chamber 74 are interchanged.

It will however be noted that the portion 78a of chamber 74a which is selectively placed under high and low pressures is disposed on the side of piston 76a adjacent the wall incorporating bore 82a.

The operation of the bypass unloader shown in FIG- URE 3 is similar to that of FIGURE 2. Thus when coil 98 is energized to move operator 96a to the left, first portion 7 8a of chamber 74a is communicated with and placed at the pressure of suction passageway 51 via passageways 92a and 94a whereby the differential pressure on piston 76a forces valve 68a to the closed position via stem 70a thereby loading the compressor. It will be understood that second portion a of chamber 74a is in continuous communication with passageway 56 via passageway 86a and that the effective area of piston 76a is sufficiently greater than the face area of valve seat 66a so that valve 68a will close in spite of the differential pressure acting on valve 68a. When coil 98 is (i6-6I1C1gl26d and operator 96a is moved to the right position by action of bias sping 99a, portion 78a of chamber 741: is communicated with and placed at the pressure of passageway 56 via passageways 90a and 94a equalizing the pressure on both sides of piston 76a whereupon the differential pressure on valve 68a forces valve 68a to the open position thereby unloading the compressor.

The form of the invention shown in FIGURE 4 is similar to that shown in FIGURE 2 and elements having similar functions have been identified by similar reference numerals followed by the sufiix The form of the invention shown in FIGURE 4 differs from that of FIG- URE 2 mainly in that a selector valve 88b of the two-way type is employed rather than a three-way valve as in the form shown in FIGURE 2. Two-way solenoid valve 8812 has an inlet port which communicates with passageway 94]) similar to passageway 94. Valve 88b also has an outlet port which communicates with passageway 92b similar to passageway 92. In addition the form of the invention shown in FIGURE 4 has a restrictor passageway 104 communicating passageway 56 with first portion 78b of chamber 74b. It should be understood that the term restrictor passageway as used hereinafter may be a passageway relatively large in cross-section having a restrictive portion or restrictor orifice therein. Passageways 104, 94/2 and 92b define together a control passageway for controlling the pressure in first portion 78b of chamber 74b. Port operator 96b controls the flow from passageway 94!) to passageway 92b.

Thus when coil 98 is energized to move operator 96b to the right, first portion 78b of chamber 74b is communicated with passageway 51 via passageway 92b and 94b. Passageways 92b and 9412 are sufficiently large so as to bleed off the flow of fluid passing in restrictor passageway 104 without materially raising the pressure in the first portion 78b of chamber 74b whereby the differential pressure on piston 76b forces valve 68b to the closed position via stem 7% thereby loading the compressor. When coil 98 is de-energized and operator 96b is moved to the left position by action of bias spring 9912 terminating flow from passageway 94b to passageway 92b, pressure in portion 78b of chamber 74b is increased to that of passageway 56 via the fluid passing in restrictor passageway 104 equalizing the pressures on both sides of piston 76b whereupon the differential pressure on valve 68b forces valve 68b to the open position thereby unloading the compressor.

The form of the invention shown in FIGURE 5 is similar to that shown in FIGURE 3 and elements having similar functions have been identified by similar reference numerals followed by the sufiix c. The form of the invention shownin FIGURE 4 differs from that of FIGURE 3 mainly in that a selector valve 88c of the two-way type is employed rather than a three-way valve as in the form shown in FIGURE 3. Two-way solenoid valve 880 has an inlet port which communicates with passage 94c similar to passageway 94. Valve 88c also has an outlet port which communicates with passageway 920 similar to passageway 92. In addition the form of the invention shown in FIGURE 5 has a restrictor passageway 106 communicating passageway 56 with portion 780 of chamber 740. Passageways 106, 94c and 920 together define a control passageway for controlling the pressure in first portion 78c of chamber 740. Port operator 960 controls the fiow from passageway 940 to passageway 926.

Thus when coil 98 is energized to move operator 960 to the left, first portion 780 of chamber 740 is communicated with passageway 51 via passageways 94c and 920. Passageways 92c and 940 are sufficiently large so as to bleed off the flow of fluid passing in restrictor passageway 106 without materially raising the pressure in first portion 78c of chamber 740 whereby the differential pressure on piston 76c forces valve 680 to the closed position via stem 70c thereby loading the compressor. When coil 98 is de-energized and operator 960 is moved to the right position by action of bias spring 99c terminating flow from passage 940 to passageway 92c, pressure in portion 78c of chamber 740 is increased to that of passageway 56 via the fluid passing in restrictor passageway 106 equalizing the pressure on both sides of piston 76b whereupon the differential pressure on valve 68c forces valve 68c to the open position thereby unloading the compressor.

In each of the aforedescribed forms of the invention it will be apparent that the bypass valve is disposed on the downstream side of its seat so gas pressure differential across the valve opens the valve. Also there is a piston connected to the valve for closing the valve. One side of the piston is continuously under high side. or discharge pressure for closing the valve. In each form opening of the valve is accomplished by applying high side pressure to the other side of the piston thereby substantially balancing the forces on the piston and permitting the bypass valve to open by the differential pressures on the valve. Conversely, closure of the valve is effected by relief of the pressure on said other side of the piston. In each form the effective area of the piston must be greater than that of the bypass valve face so that the piston can effect closure of the bypass valve in spite of differential pressure on the bypass valve. While the arrangement described does not require the use of a spring to motivate the valve to either the closed or open position it is contemplated that a weak spring might be used to bias the valve in one direction or the other to merely effect trimming or adjustment of the valve.

Although I have described in detail the preferred embodiment of my invention, I contemplate that many changes may be made without departing from the scope or spirit of my invention and I desire to be limited only by the claims.

I claim:

1. A refrigeration system comprising a refrigerant compressor means, a refrigerant condenser, a refrigerant throttling means and a refrigerant evaporator connected respectively in series, said compressor means including first and second compression cylinders each including a movable piston therein, each of said cylinders having associated therewith a suction port and a discharge port provided respectively with a suction valve and a discharge valve, a suction passageway extending to said suction ports from said evaporator, a first discharge passageway extending from the discharge port of said first cylinder to said condenser, a second discharge passageway extending from the discharge port of said second cylinder and communicating with said first discharge passageway, a check valve means disposed in said second discharge passageway substantially limiting flow therethrough to a flow direction away from said discharge port of said second cylinder, a bypass passageway communicating with said discharge port of said second cylinder upstream of said check valve means and extending to said suction passageway, a bypass unloader valve means disposed in said bypass passageway for controlling the flow of fluid from said discharge port of said second cylinder through said bypass passageway to said suction passageway, said valve mean including a valve seat, a valve disposed on the downstream side of said seat in cooperative relationship with said seat, means forming a chamber, a movable partition dividing said chamber into first and second portions, connecting means operatively connecting said partition to said valve whereby movement of said partition toward said first portion of said chamber moves said valve toward said seat and movement of said valve away from said seat moves said partition toward said second portion of said chamber, means communicating said second portion of said chamber with said first discharge passageway on the downstream side of said check valve means, and selector means for selectively applying first cylinder discharge pressure and suction pressure to said first portion of said chamber whereby said bypass valve is respectively opened and closed.

2. The apparatus as defined by claim 1 wherein said connecting means extends through a wall of said chamber.

3. The apparatus defined by claim 2 wherein said selector means includes means for selectively communicating said first portion of said chamber with said suction passageway and with said first discharge passageway on the downstream side of said check valve means.

4. The apparatus as defined by claim 3 wherein said chamber is cylindrical and said partition is a piston slidably mounted therein.

5. The apparatus as defined by claim 3 wherein said connecting means extends through a wall of said first portion of said chamber and the area of the side of said partition facing said second portion of said chamber is greater than the face area of said valve seat.

6. The apparatus as defined by claim 3 wherein said connecting means extends through a wall of said second portion of said chamber and the area of the side of said partition facing said first portion of said chamber is greater than the face area of said valve seat.

7. The apparatus as defined by claim 2 wherein said selector means includes a control passageway extending from said first discharge passageway on the downstream side of said check valve means to said. suction passageway, a two way valve disposed in said control passageway for selectively terminating the flow therethrough a restrictor disposed in said control passageway upstream of said two way valve for restricting the flow through said control passageway and means providing fluid communication between said first portion of said chamber and a point in said control passageway upstream of said two way valve and downstream of said restrictor.

8. The apparatus as defined by claim 7 wherein said chamber is cylindrical and said partition is a piston slidably mounted therein.

9. The apparatus as defined by claim 7 wherein said connecting means extends through a wall of said first portion of said chamber and the area of the side of said partition facing said second portion of said chamber is greater than the face area of said valve seat.

10. The apparatus as defined by claim 7 wherein said connecting means extends through a wall of said second portion of said chamber and the area of the side of said partition facing said first portion of said chamber is greater than the face area of said valve seat.

References Cited UNITED STATES PATENTS 2,165,741 7/1939 Wolfert 62-196 2,715,992 8/1955 Wilson 62196 XR MEYER 'PERLIN, Primary Examiner. 

1. A REFRIGERATION SYSTEM COMPRISING A REFRIGERANT COMPRESSOR MEANS, A REFRIGERANT CONDENSER, A REFRIGERANT THROTTLING MEANS AND A REFRIGERANT EVAPORATOR CONNECTED RESPECTIVELY IN SERIES, SAID COMPRESSOR MEANS INCLUDING FIRST AND SECOND COMPRESSION CYLINDERS EACH INCLUDING A MOVABLE PISTON THEREIN, EACH OF SAID CYLINDERS HAVING ASSOCIATED THEREWITH A SUCTION PORT AND A DISCHARGE PORT PROVIDED RESPECTIVELY WITH A SUCTION VALVE AND A DISCHARGE VALVE, A SUCTION PASSAGEWAY EXTENDING TO SAID SUCTION PORTS FROM SAID EVAPORATOR, A FIRST DISCHARGE PASSAGEWAY EXTENDING FROM THE DISCHARGE PORT OF SAID FIRST CYLINDER TO SAID CONDENSER, A SECOND DISCHARGE PASSAGEWAY EXTENDING FROM THE DISCHARGE PORT OF SAID SECOND CYLINDER AND COMMUNICATING WITH SAID FIRST DISCHARGE PASSAGEWAY, A CHECK VALVE MEANS DISPOSED IN SAID SECOND DISCHARGE PASSAGEWAY SUBSTANTIALLY LIMITING FLOW THERETHROUGH TO A FLOW DIRECTION AWAY FROM SAID DISCHARGE PORT OF SAID SECOND CYLINDER, A BYPASS PASSAGEWAY COMMUNICATING WITH SAID DISCHARGE PORT OF SAID SECOND CYLINDER, UPSTREAM OF SAID CHECK VALVE MEANS AND EXTENDING TO SAID SUCTION PASSAGEWAY, A BYPASS UNLOADER VALVE MEANS DISPOSED IN SAID BYPASS PASSAGEWAY FOR CONTROLLING THE FLOW OF FLUID FROM SAID DISCHARGE PORT OF SAID SECOND CYLINDER THROUGH SAID BYPASS PASSAGEWAY TO SAID SUCTION PASSAGEWAY, SAID VALVE MEAN INCLUDING A VALVE SEAT, A VALVE DISPOSED ON THE DOWNSTREAM SIDE OF SAID SEAT IN COOPERATIVE RELATIONSHIP WITH SAID SEAT, MEANS FORMING A CHAMBER, A MOVABLE PARTITION DIVIDING SAID CHAMBER INTO FIRST AND SECOND PORTIONS, CONNECTING MEANS OPERATIVELY CONNECTING SAID PARTITION TO SAID VALVE WHEREBY MOVEMENT OF SAID PARTITION TOWARD SAID FIRST PORTION OF SAID CHAMBER MOVES SAID VALVE TOWARD SAID SEAT AND MOVEMENT OF SAID VALVE AWAY FROM SAID SEAT MOVES SAID PARTITION TOWARD SAID SECOND PORTION OF SAID CHAMBER, MEANS COMMUNICATING SAID SECOND PORTION OF SAID CHAMBER WITH SAID FIRST DISCHARGE PASSAGEWAY ON THE DOWNSTREAM SIDE OF SAID CHECK VALVE MEANS, AND SELECTOR MEANS FOR SELECTIVELY APPLYING FIRST CYLINDER DISCHARGE PRESSURE AND SUCTION PRESSURE TO SAID FIRST PORTION OF SAID CHAMBER WHEREBY SAID BYPASS VALVE IS RESPECTIVELY OPENED AND CLOSED. 